src/glsl/ast_array_index.cpp

   1 /*
   2  * Copyright © 2010 Intel Corporation
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  21  * DEALINGS IN THE SOFTWARE.
  22  */
  23
  24 #include "ast.h"
  25 #include "glsl_types.h"
  26 #include "ir.h"
  27
  28
  29 /**
  30  * If \c ir is a reference to an array for which we are tracking the max array
  31  * element accessed, track that the given element has been accessed.
  32  * Otherwise do nothing.
  33  *
  34  * This function also checks whether the array is a built-in array whose
  35  * maximum size is too small to accommodate the given index, and if so uses
  36  * loc and state to report the error.
  37  */
  38 static void
  39 update_max_array_access(ir_rvalue *ir, unsigned idx, YYLTYPE *loc,
  40                         struct _mesa_glsl_parse_state *state)
  41 {
  42    if (ir_dereference_variable *deref_var = ir->as_dereference_variable()) {
  43       ir_variable *var = deref_var->var;
  44       if (idx > var->data.max_array_access) {
  45          var->data.max_array_access = idx;
  46
  47          /* Check whether this access will, as a side effect, implicitly cause
  48           * the size of a built-in array to be too large.
  49           */
  50          check_builtin_array_max_size(var->name, idx+1, *loc, state);
  51       }
  52    } else if (ir_dereference_record *deref_record =
  53               ir->as_dereference_record()) {
  54       /* There are two possibilities we need to consider:
  55        *
  56        * - Accessing an element of an array that is a member of a named
  57        *   interface block (e.g. ifc.foo[i])
  58        *
  59        * - Accessing an element of an array that is a member of a named
  60        *   interface block array (e.g. ifc[j].foo[i]).
  61        */
  62       ir_dereference_variable *deref_var =
  63          deref_record->record->as_dereference_variable();
  64       if (deref_var == NULL) {
  65          if (ir_dereference_array *deref_array =
  66              deref_record->record->as_dereference_array()) {
  67             deref_var = deref_array->array->as_dereference_variable();
  68          }
  69       }
  70
  71       if (deref_var != NULL) {
  72          if (deref_var->var->is_interface_instance()) {
  73             const glsl_type *interface_type =
  74                deref_var->var->get_interface_type();
  75             unsigned field_index =
  76                deref_record->record->type->field_index(deref_record->field);
  77             assert(field_index < interface_type->length);
  78             if (idx > deref_var->var->max_ifc_array_access[field_index]) {
  79                deref_var->var->max_ifc_array_access[field_index] = idx;
  80
  81                /* Check whether this access will, as a side effect, implicitly
  82                 * cause the size of a built-in array to be too large.
  83                 */
  84                check_builtin_array_max_size(deref_record->field, idx+1, *loc,
  85                                             state);
  86             }
  87          }
  88       }
  89    }
  90 }
  91
  92
  93 ir_rvalue *
  94 _mesa_ast_array_index_to_hir(void *mem_ctx,
  95                              struct _mesa_glsl_parse_state *state,
  96                              ir_rvalue *array, ir_rvalue *idx,
  97                              YYLTYPE &loc, YYLTYPE &idx_loc)
  98 {
  99    if (!array->type->is_error()
 100        && !array->type->is_array()
 101        && !array->type->is_matrix()
 102        && !array->type->is_vector()) {
 103       _mesa_glsl_error(& idx_loc, state,
 104                        "cannot dereference non-array / non-matrix / "
 105                        "non-vector");
 106    }
 107
 108    if (!idx->type->is_error()) {
 109       if (!idx->type->is_integer()) {
 110          _mesa_glsl_error(& idx_loc, state, "array index must be integer type");
 111       } else if (!idx->type->is_scalar()) {
 112          _mesa_glsl_error(& idx_loc, state, "array index must be scalar");
 113       }
 114    }
 115
 116    /* If the array index is a constant expression and the array has a
 117     * declared size, ensure that the access is in-bounds.  If the array
 118     * index is not a constant expression, ensure that the array has a
 119     * declared size.
 120     */
 121    ir_constant *const const_index = idx->constant_expression_value();
 122    if (const_index != NULL && idx->type->is_integer()) {
 123       const int idx = const_index->value.i[0];
 124       const char *type_name = "error";
 125       unsigned bound = 0;
 126
 127       /* From page 24 (page 30 of the PDF) of the GLSL 1.50 spec:
 128        *
 129        *    "It is illegal to declare an array with a size, and then
 130        *    later (in the same shader) index the same array with an
 131        *    integral constant expression greater than or equal to the
 132        *    declared size. It is also illegal to index an array with a
 133        *    negative constant expression."
 134        */
 135       if (array->type->is_matrix()) {
 136          if (array->type->row_type()->vector_elements <= idx) {
 137             type_name = "matrix";
 138             bound = array->type->row_type()->vector_elements;
 139          }
 140       } else if (array->type->is_vector()) {
 141          if (array->type->vector_elements <= idx) {
 142             type_name = "vector";
 143             bound = array->type->vector_elements;
 144          }
 145       } else {
 146          /* glsl_type::array_size() returns -1 for non-array types.  This means
 147           * that we don't need to verify that the type is an array before
 148           * doing the bounds checking.
 149           */
 150          if ((array->type->array_size() > 0)
 151              && (array->type->array_size() <= idx)) {
 152             type_name = "array";
 153             bound = array->type->array_size();
 154          }
 155       }
 156
 157       if (bound > 0) {
 158          _mesa_glsl_error(& loc, state, "%s index must be < %u",
 159                           type_name, bound);
 160       } else if (idx < 0) {
 161          _mesa_glsl_error(& loc, state, "%s index must be >= 0",
 162                           type_name);
 163       }
 164
 165       if (array->type->is_array())
 166          update_max_array_access(array, idx, &loc, state);
 167    } else if (const_index == NULL && array->type->is_array()) {
 168       if (array->type->is_unsized_array()) {
 169          _mesa_glsl_error(&loc, state, "unsized array index must be constant");
 170       } else if (array->type->fields.array->is_interface()
 171                  && array->variable_referenced()->data.mode == ir_var_uniform) {
 172          /* Page 46 in section 4.3.7 of the OpenGL ES 3.00 spec says:
 173           *
 174           *     "All indexes used to index a uniform block array must be
 175           *     constant integral expressions."
 176           */
 177          _mesa_glsl_error(&loc, state,
 178                           "uniform block array index must be constant");
 179       } else {
 180          /* whole_variable_referenced can return NULL if the array is a
 181           * member of a structure.  In this case it is safe to not update
 182           * the max_array_access field because it is never used for fields
 183           * of structures.
 184           */
 185          ir_variable *v = array->whole_variable_referenced();
 186          if (v != NULL)
 187             v->data.max_array_access = array->type->array_size() - 1;
 188       }
 189
 190       /* From page 23 (29 of the PDF) of the GLSL 1.30 spec:
 191        *
 192        *    "Samplers aggregated into arrays within a shader (using square
 193        *    brackets [ ]) can only be indexed with integral constant
 194        *    expressions [...]."
 195        *
 196        * This restriction was added in GLSL 1.30.  Shaders using earlier
 197        * version of the language should not be rejected by the compiler
 198        * front-end for using this construct.  This allows useful things such
 199        * as using a loop counter as the index to an array of samplers.  If the
 200        * loop in unrolled, the code should compile correctly.  Instead, emit a
 201        * warning.
 202        */
 203       if (array->type->element_type()->is_sampler()) {
 204          if (!state->is_version(130, 100)) {
 205             if (state->es_shader) {
 206                _mesa_glsl_warning(&loc, state,
 207                                   "sampler arrays indexed with non-constant "
 208                                   "expressions is optional in %s",
 209                                   state->get_version_string());
 210             } else {
 211                _mesa_glsl_warning(&loc, state,
 212                                   "sampler arrays indexed with non-constant "
 213                                   "expressions will be forbidden in GLSL 1.30 "
 214                                   "and later");
 215             }
 216          } else {
 217             _mesa_glsl_error(&loc, state,
 218                              "sampler arrays indexed with non-constant "
 219                              "expressions is forbidden in GLSL 1.30 and "
 220                              "later");
 221          }
 222       }
 223    }
 224
 225    /* After performing all of the error checking, generate the IR for the
 226     * expression.
 227     */
 228    if (array->type->is_array()
 229        || array->type->is_matrix()) {
 230       return new(mem_ctx) ir_dereference_array(array, idx);
 231    } else if (array->type->is_vector()) {
 232       return new(mem_ctx) ir_expression(ir_binop_vector_extract, array, idx);
 233    } else if (array->type->is_error()) {
 234       return array;
 235    } else {
 236       ir_rvalue *result = new(mem_ctx) ir_dereference_array(array, idx);
 237       result->type = glsl_type::error_type;
 238
 239       return result;
 240    }
 241 }